"Beside the gates, at the opening to the city, at the entrance of the doors, she cries out"
The place described is the place that the elders of the city sat to conduct business and to govern the city. He is saying that wisdom resides in and near the place where the elders and successful businessmen are. They have done it. They have accomplished a level of success that has put them in a position to advise others who have not done it.
The key idea is that you should listen to what the leaders who have done it would say about your idea. You should be willing to listen to what these highly respected leaders say about success and prosperity and life. Wisdom is not hidden; it is out in the open in these men. They want to advise you. Listen to them.
These men have made many of the mistakes you are thinking about and have overcome those mistakes in order to have a level of prosperity that does not require them to be out in the field or store every day. They can dedicate a high level of their time to governing the city.
Now the type of thinking in this proverb is that those who have been successful and have lived life should give back to the community by governing. In this time the governors or leaders were highly revered people; not reviled as lying politicians. If you have a question, make sure you get the counsel of those who have already successfully navigated the waters you are about to sail in.
Wisdom is the triple-win: the win for God, the win for others, and the win for yourself. The kind of choices that result in this type of winning and understanding requires that you listen to the voice of experience. The choices that result in real winning over the long term are not always easily determined.